add FE_cos, FE_sin ad optimize

src/FxEngine/FxEngine.c

@@ -1,4 +1,5 @@
 #include "FxEngine.h"
+
 #include <libprof.h>
 #include <display.h>
 

src/FxEngine/math/functions.c

@@ -0,0 +1,43 @@
+#include "functions.h"
+
+static const double pi2=pi*2;
+static const double pi_sur2=pi/2;
+// cos (0<x<pi/2)
+
+
+static double reducted_cos(const double& a)
+{
+    double u=1.0;
+    double a2=a*a;
+    // p doit toujours être un nombre impair >1
+    for(int p=13;p>=1;p-=2)
+        u=1-a2/(p*p+p)*u;
+    return u;
+}
+
+static void modulo_2pi(double& a)
+{
+    while (a<=-pi2) a+=pi2;
+    while (a>pi2) a-=pi2;
+    return a;
+}
+
+double FE_cos(double angle)
+{
+    modulo_2pi(angle);
+    int angle_arrondi=(int)(angle/pi_sur2);
+    switch (angle_arrondi)
+    {
+        case -2:
+        case 1:
+        return -reducted_cos(angle);
+        case -1:
+        case 0:
+        return reducted_cos(angle);
+    }
+}
+
+double FE_sin(double angle)
+{
+    return FE_cos(angle-pi_sur2);
+}

src/FxEngine/math/functions.h

@@ -0,0 +1,12 @@
+#ifndef FE_FUNCTIONS_H
+#define FE_FUNCTIONS_H
+
+const extern double pi=3.141592653589793238462643383279
+
+double FE_cos(double angle);
+double FE_sin(double angle);
+
+
+
+
+#endif